The Covid era restrictions on passenger aircraft, including mask mandates and negative tests, are officially ended. From now on, any American traveling domestically or returning to the United States from a foreign nation does not have to wear a mask, does not have to provide a negative Covid test, and does need to present proof of vaccination. We have returned to a pre-Covid aviation industry, which offers several dangers as Covid continues to loom large.
As more people resume standard travel practices, Covid transmission on airplanes will increase. As the government and airlines roll back passenger Covid protections, it is now up to individuals to take every measure to protect themselves from infection. Continuing our series on air travel during Covid, here we will discuss the intricacies of Covid transmission on aircraft and how individuals can protect themselves from Covid on upcoming flights.
Recently, the National Academy of Sciences, Engineering, and Medicine released a report detailing aviation in the Covid-19 era. This report presents science-based risks and mitigation for passengers flying commercial aircraft, which we will use to guide our discussion.
Being in the same plane as another passenger infected with Covid-19 does not guarantee transmission to everyone on board. The likelihood of infection is low unless you are sitting within two or three rows of an infected person. Air in airplanes does have a higher CO2 count than outside or indoors, which means your chances of contracting Covid-19 in a plane are higher than at home or the park, but still not guaranteed. CO2 in enclosed spaces such as an airplane is generally the result of the gas, as well as infectious particles, in other people’s exhalations.
The air you breathe is ventilated, reoxygenated, filtered, and sent back into the cabin to be breathed again. However, the air is circulated along the circumference of the cylindrical plane, not lengthwise. This means that the air you breathe is mainly shared between those in your row and those directly near you. The process is far from perfect. We recently monitored the CO2 concentration several hours into a flight on a domestic airline and found it to be four times that of the open air.
A study of a Vietnam Airlines flight from London to Vietnam examined the importance of proximity. Of the 217 passengers and crew aboard, one passenger displayed symptoms of Covid-19 mid-flight. Later on, 14 passengers and one crew member tested positive. Notably, 11 of the 14 passengers were sitting within two meters of the symptomatic carrier.
These results are mirrored in several studies in the National Academy of Sciences, Engineering, and Medicine report. One simulation found that the general odds of Covid infection for a passenger on a full flight is one in 3,900. These odds increase drastically, as high as 80% if sitting in direct proximity to an infected person without a mask. Notably, the same simulation found that rigorously enforced mask-wearing drops transmission odds significantly; however, no US-based airlines now enforce mask-wearing.
The SARS-CoV-2 virus transmits in three ways. First, via droplets such as sneezing and coughing. Masks would essentially erase the risks of droplet transmission. Still, US District Judge Kathryn Kimball Mielle of Florida saw fit to overrule the federal mask mandate, meaning mask usage on domestic airlines is optional.
The second transmission method is aerosols, which are like droplets but much smaller produced by breathing. Aerosol transmission is how the typical asymptomatic carrier passes on Covid-19. Again, aerosol risks would be mitigated by masks.
The third transmission method is via fomites, or surfaces that infectious particles may latch. An infected person may have trace virus on their hands from touching their eyes, nose, or mouth, and by touching an object, they leave trace virus for another potential carrier to pick up. This could manifest in an airplane as handing something to the flight attendant, touching the bathroom handle, etc. This transmission method is easily mitigated by standard hand sanitizer and general health practices like avoiding touching your face.
Depending on the level of community transmission, the chance that one person infected with Covid-19 boards a plane is relatively high. For instance, the report notes that in Texas, which at the time of writing had a Covid rate of 73 cases per 100,000 people, there is a 46% chance that one passenger on a 100-passenger plane has Covid. This number skyrockets to 96% when considering many cases are undiagnosed.
As the federal government and airlines have rolled back nearly all Covid-19 restrictions, it is up to the individual to protect themselves against these chances. The report recommends non-pharmaceutical interventions like N95 masks, keeping as socially distant from others as possible, move about the plane as little as possible, use hand sanitizer regularly for personal use and on surfaces.
Additionally, strategic flight bookings could reduce the chances of transmission as well. For instance, flights departing on Tuesdays, Wednesdays, and Thursdays are less crowded than those leaving on Friday through Monday. Try to book midweek flights and select a seat beside an empty middle seat, if possible.
Covid remains prevalent, and the risk of infection mid-flight is significant, but maintaining safe Covid practices could prevent a case of Covid that would have otherwise derailed your trip and potentially caused long-term issues for months and years.